I had a bad experience with Champion plugs back in 1972. I put 2 new Champion plugs into my 1971 650 Triumph Bonneville, started it, drove it into my basement, shut it off, removed the battery, then drained the carbs and fuel tank for winter storage. The following spring, I installed the freshly charged battery, put fresh fuel into the tank, "tickled" the carbs (no choke on the AMAL carbs - the tickler flooded the fuel bowl in lieu of choking) and tried to start it so I could drive it out of the basement. To my astonishment, it would not start. It didn't even fire or try to start. I took the brand new Champion plugs out, laid them on the head with the wires attached and kicked the motor over. The plugs had a good, strong, blue spark. I sprayed some starting fluid in the plug holes, installed the plugs and tried again - nothing! I then went through the complete troubleshooting procedure (compression, points, carbs) and still not even a cough. Finally I decided to start over. What's the first thing you do when a known good running engine won't start? REPLACE THE PLUGS! I got two new Nippon Denso plugs, screwed them in and the motor started on the first kick. I could not believe the Champions (which had only been run less than 10 minutes) could be bad, so I put them back in and the warm motor would not start - not even a sputter. I've still got the bike and it's still got those ND plugs in it. It ran fine the last I got it out (2005) and I'm sure it will start the next time I get it out. I use NGK plugs now because I can't seem to find the ND's. I have Autolites in my T-bird (with 114,000 miles on them) and AC Delcos in my Dakota (took out the Champions at 33,000 miles due to hard starting and poor fuel milage). The Dakota (RT with 5.9L motor) now has 90,000 miles on it, starts instantly in our near zero temps and has had no discernable decrease in fuel economy. I have seen more motors that had a Champion plug that wouldn't start (where changing the plug would make it run) than motors that had NGK, ND, Autolite, AC or any other plug that had the same problem. I am simply biased against a Champion Spark Plug due to my experience with them. I could go into the construction differences between Champion and other plugs, but that is a 30 page disertation.